Process of bleaching textiles with lower alkyl quaternary ammonium perhalides



United States Patent This invention relates to organic bleachingcompositions having advantageous properties.

Compounds and compositions capable of releasing chlorine have long beenknown and used for bleaching and stain removal. Inorganic hypochlorites,particularly sodium hypochlorite, are widely used for the purpose.Sodium hypochlorite, although recognized as an effective and relativelycheap bleaching agent, has certain inherent disadvantages. Because ofits instability, it can be handled only as a dilute aqueous solutionrequiring bulky and inconvenient containers and having a limited shelflife. Hypochlorites also have a damaging effect on fabric tensilestrength. Recently, organic nitrogen compounds containingnitrogen-bonded chlorine atoms in their structure have been offered forbleaching use, for example, trichloroisocyanuric acid, potassiumdichloroisocyanurate, dichlorodirnethylhydantoin, and related compounds.These have the advantage of being solids and therefore are capable ofbeing formulated into solid bleaching compositions, bleaching cleansers,and the like. However, these materials are not entirely suitable for thepurpose, having one or more of such disadvantages as poor dry stability,insufiicient water solubility, or low bleaching efficiency.

Chlorine-liberating bleaches such as those described above also tend toattack the structure of many textile fibers, causing yellowing and aloss of tensile strength. This elfect is particularly noticeable infibers having nitrogen atoms associated with their structure; forexample, silk, wool, synthetic polyamides, or fibers coated orimpregnated with nitrogen-containing materials such as melamineresin-finished cotton.

It has now been found that many of the above-mentioned disadvantages arelargely overcome or avoided by the use as bleaches of certain tetraalkylammonium perhalides. Most effective for the purpose are the perhalideshaving the structure R NBr Cl( wherein each R is a lower alkyl radicalcontaining 1-6 carbon atoms and n is an integer from one to threeinclusive. The compounds included are therefore the tetraalkyl ammoniumdichlorobromides, dibromochlorides, and tribromides. Most preferred,particularly on economic grounds, are the dichlorobromides. Compoundswherein at least three Rs are methyl are advantageous because of theirrelatively higher water solubility.

The perhalide compounds described above have been found to be effectiveand advantageous bleaching agents when applied in water dispersion tovarious substances having undesirable and bleachable color or stain.Straw, Wood pulp, paper stock, leather, various natural fibers such ascotton, silk, wool, and linen, and synthetic polyamide, polyester, andother like fibers may be treated by this process to remove natural orforeign discoloration.

These perhalides are crystalline solids which are stable while dry andthey may be incorporated as bleaching components of various dryformulations for household and industrial use. The tetraalkyl ammoniumperhalides are relatively soluble in water and, when so dissolved,readily liberate two atoms of halogen per molecule. Dichlorobromidesliberate one atom each of chlorine and bromine while dibromochloridesand tribromides liberate two atoms of bromine.

These compounds have been found to have particular advantage in thebleaching of fabrics which have been treated with nitrogen-containingresins for crease resistance. Specifically, melamine resin-treatedcotton may be bleached by these compounds with less yellowing andweakening of the fabric than is possible with the commonly used chlorinebleaches. These results are obtained along with bleaching eflicienciesat least as high as those shown by chorine-liberating bleaches when usedin equivalent halogen concentrations.

EXAMPLE 1 One liter portions of water in stainless steel beakers wereheated to 130 F., the bleaching compounds to be tested were dissolved inthe respective beakers of water, and the pH of each test solution wasadjusted to 9-10 where necessary by the addition of tetrapotassiumpyrophosphate. Bleaching efficiencies were measured at concentrations of300 p.p.m. available halogen calculated as chlorine. Available halogenwas determined by titration of iodine released from an acidified KIsolution by a known quantity of perhalide. Three 5-inch squares ofunbleached cotton sheeting were bleached for 10 minutes with agitationin each test solution, the cloths were rinsed 5 minutes in water, andthey were pressed dry with a hand iron. The average reflectance of thethree swatches of cotton sheeting as measured by a reflectometer wastaken as a measure of bleach performance. The figures given arepercentages based on a magnesium oxide block standard which is assigneda value of reflectance.

Table I Bleaching compound: Average reflectance Sodium hypochlorite 84.5(CH C H NBrCl 84.3 (CH3)3C2H5NC1BI2 (CH C H NBrCl 84.2 (CH NBrCl 84.3

EXAMPLE 2 In the manner described above, samples of white melamineresin-finished cotton print cloth were treated with various bleachingcompounds and rinsed with water. These samples were dried in an electricdryer and inspected visually for yellowing. Table 2 lists data obtainedat bleach concentrations of 300, 500, and 700 p.p.m. available halogenas chlorine.

Table II Relative Yellowing Bleaching Compounds 300 p.p.m. 500 p.p.m.

700 p.p.m. C1 C1 C12 Moderatedo..

Sodium hypochlorite Potassium dichloroisocya Heavy. Moderate.

Very slight. Do.

Do. Do.

Very slight" Very slight d do do do EXAMPLE 3 Table III TensileStrength, lbs.

Bleaching Compound Regular Resin- Cotton finished Cotton Sodiumhypochlorite 40.3 27 6 Potassium dichloroisocyanurate 34.3 28 1 (CH3)C2H5NBIC12 38. 3 31. 6 (CI-Ia)aO H NClBr 41. 2 34. 9 (CH3) 3C4H9NBIC1;37.5 33. 5 (C1I3)4NBIO]2 40.8 33 0 Blank 51. 3 33 8 The tetraalkylammonium perhalides are also advantageous in that they are effectivebleaching agents in acidic solutions although best results are obtainedat high pH levels, a pH of about 911 being preferred. Additionally, atboth high and low pH, these compounds are not only eflicient bleaches,but also show low redeposition of stain upon the bleached fabric. Afurther advantage of these perhalides lies in the biocidal free halogenwhich is liberated upon contact with water, thereby making thesecompounds disinfectants as well as bleaches.

I claim:

1. A process for bleaching natural and synthetic fibers which comprisesapplying to said fibers a Water dispersion having dissolved therein aneffective amount of a compound having the structure R NBr Cl whereineach R is a lower alkyl radical containing about 1-6 carbon atoms and nis an integer from one to three inclusive.

2. The process of claim 1 where in n is one.

3. The process of claim 2 wherein at least three of the Rs are methylradicals.

4. The process of claim 2 wherein the fiber bleached is melamineresin-finished cotton.

References Cited in the file of this patent UNITED STATES PATENTS2,256,958 Muskat Sept. 23, 1941 2,430,233 Magill Nov. 4, 1947 2,913,460Brown Nov. 17, 1959 2,929,816 Chamberlain May 22, 1960 2,945,061Habernickel July 12, 1960 2,972,620 Simmons Feb. 21, 1961 2,980,488Kokorudz Apr. 18, 1961 S- PATENT OFFICE OF CORRECTION November l0 UNITEDSTATE CERTIFICATE Patent No Jack mbered pat- T1; is hereby c on and thatthe said Le ent requiring correcti (1 below.

lowing:

correc'te after line 23, insert the fol Column l,

OTHER REFERENCES Chattaway et al, q Jo Chem. Soc; (London) l23 Pages(1923) through l1 Ghemo Abstr. 1949 (1923). n.

y of April 1965.

(SEAL) Commissioner of Patents ERNEST W. SWlDER Attest'mg Officer

1. A PROCESS FOR BLEACHING NATURAL AND SYNTHETIC FIBERS WHICH COMPRISES APPLYING TO SAID FIBERS A WATER DISPERSION HAVING DISSOLVED THEREIN AN EFFECTIVE AMOUNT OF A COMPOUND HAVING THE STRUCTURE R4NBRNCL(3-N) WHEREIN EACH R IS A LOWER ALKYL RADICAL CONTAINING ABOUT 1-6 CARBON ATOMS AND N IS AN INTEGER FROM ONE TO THREE INCLUSIVE. 